Self-consistent Disk-reflection Analysis of the Black Hole Candidate X-Ray Binary MAXI J1813−095 with NICER, Swift, Chandra, and NuSTAR

Abstract We present our analysis of MAXI J1813−095 during its hard state “stalled” outburst in 2018. This self-consistent analysis has been carried out using the Neutron Star Interior Composition Explorer, Swift, Chandra, and NuSTAR throughout seven observations of MAXI J1813−095. We find a relativistic iron line at ∼6.5 keV from the inner region of the accretion disk. Our results are consistent with a slightly truncated disk or nontruncated disk for an inner radius of ∼2 R g and minimum spin of >0.7 with the best value of ∼0.9, assuming R in reaches the innermost stable circular orbit at L x ∼ 1% L Edd . We analyzed MAXI J1813−095 over its outburst, employing a spectral model that self-consistently couples the seed disk photons to the Comptonization and reflection components, also inclusive of reflection Comptonization. The unique aspect of this work is a reflection fraction of order unity, which is significantly higher than previous studies of this source and is a consequence of applying the self-consistent disk-Comptonization-reflection spectral model. Other key parameters, such as inclination and inner radius, are found to be consistent with other works.